package com.tmc.util;

import java.security.MessageDigest;

/**
 * 采用MD5加密解密
 * 
 * @author tfq
 * @datetime 2011-10-13
 */
public class MD5Util {

	/**
	 * MD5算法
	 * @param laintext
	 * @return
	 */
	public static String MD5(String laintext) {
		String re_md5 = new String();
		try{
			MessageDigest md = MessageDigest.getInstance("MD5");
			md.update(laintext.getBytes("UTF-8"));
			byte b[] = md.digest();
			int i;
			StringBuffer buf = new StringBuffer("");
			
			for (int offset = 0; offset < b.length; offset++) {
				i = b[offset];
				if(i < 0)
					i += 256;
				if(i < 16)
					buf.append("0");	
				    buf.append(Integer.toHexString(i));
			}
			re_md5 = buf.toString(); 
		}catch (Exception e) {
			e.printStackTrace();
		}
		
		return re_md5;
	}
	
	/***
	 * MD5加码 生成32位md5码
	 */
	public static String string2MD5(String inStr) {
		MessageDigest md5 = null;
		try {
			md5 = MessageDigest.getInstance("MD5");
		} catch (Exception e) {
			System.out.println(e.toString());
			e.printStackTrace();
			return "";
		}
		char[] charArray = inStr.toCharArray();
		byte[] byteArray = new byte[charArray.length];

		for (int i = 0; i < charArray.length; i++)
			byteArray[i] = (byte) charArray[i];
		byte[] md5Bytes = md5.digest(byteArray);
		StringBuffer hexValue = new StringBuffer();
		for (int i = 0; i < md5Bytes.length; i++) {
			int val = ((int) md5Bytes[i]) & 0xff;
			if (val < 16)
				hexValue.append("0");
			hexValue.append(Integer.toHexString(val));
		}
		return hexValue.toString();

	}

	/**
	 * 加密解密算法 执行一次加密，两次解密
	 */
	public static String convertMD5(String inStr) {

		char[] a = inStr.toCharArray();
		for (int i = 0; i < a.length; i++) {
			a[i] = (char) (a[i] ^ 't');
		}
		String s = new String(a);
		return s;

	}

	// 测试主函数
	public static void main(String args[]) {
		String s = new String("peizengguo");
		System.out.println("原始：" + s);
		System.out.println("MD5后：" + string2MD5(s));
		System.out.println("加密的：" + convertMD5(s));
		System.out.println("解密的：" + convertMD5(convertMD5(s)));

	}
}
